ICAM1 and familial atrioventricular septal defect: Endothelial dysfunction (ECD) is a broad term that includes not only denudation caused by apoptosis of endothelial cells and by inability to replace desquamating cells but also reduced synthesis of molecules with a protective effect on the vasculature (i.e., nitric oxide) and the expression of proteins, such as intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), which mediate the adhesions of inflammatory cells on the surface of endothelium (endothelium activation) (59).